//==========================================================================
// Copyright (c) 2000-2008,  Elastos, Inc.  All Rights Reserved.
//==========================================================================
/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001-2003 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * $Id: read.cpp,v 1.4 2006/05/16 14:14:00 shijun Exp $
 *
 */

#include <linux/crc32.h>
#include <linux/mtd/mtd.h>
#include "nodelist.h"
#include "compr.h"
#include "jffs2_misc.h"
#include "linux/slab.h"

int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
                struct jffs2_full_dnode *fd, unsigned char *buf,
                int ofs, int len)
{
    struct jffs2_raw_inode *ri;
    size_t readlen;
    uint32_t crc;
    unsigned char *decomprbuf = NULL;
    unsigned char *readbuf = NULL;
    int ret = 0;

    ri = jffs2_alloc_raw_inode();
    if (!ri)
        return ENOMEM;

    ret = jffs2_flash_read(c, ref_offset(fd->raw), sizeof(*ri), &readlen,
                    (unsigned char *)ri);
    if (ret) {
        jffs2_free_raw_inode(ri);
        printk(KERN_WARNING "Error reading node from 0x%08x: %d\n",
                        ref_offset(fd->raw), ret);
        return ret;
    }
    if (readlen != sizeof(*ri)) {
        jffs2_free_raw_inode(ri);
        printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%zx bytes,"
                        " got 0x%zx\n", ref_offset(fd->raw), sizeof(*ri),
                        readlen);
        return EIO;
    }
    crc = crc32(0, ri, sizeof(*ri)-8);

    D1(printk(KERN_DEBUG "Node read from %08x: node_crc %08x, calculated"
                    " CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
                    ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
                    crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
                    je32_to_cpu(ri->offset), buf));
    if (crc != je32_to_cpu(ri->node_crc)) {
        printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",
               je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
        ret = EIO;
        goto out_ri;
    }
    /* There was a bug where we wrote hole nodes out with csize/dsize
       swapped. Deal with it */
    if (ri->compr == JFFS2_COMPR_ZERO
            && !je32_to_cpu(ri->dsize)
            && je32_to_cpu(ri->csize)) {
        ri->dsize = ri->csize;
        ri->csize = cpu_to_je32(0);
    }

    D1(if(ofs + len > je32_to_cpu(ri->dsize))
       {
           printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d"
                           " from %d-byte node\n", len, ofs,
                           je32_to_cpu(ri->dsize))
           ;
           ret = EINVAL;
           goto out_ri;
       }
    );

    if (ri->compr == JFFS2_COMPR_ZERO) {
        memset(buf, 0, len);
        goto out_ri;
    }

    /* Cases:
       Reading whole node and it's uncompressed - read directly to buffer
       provided, check CRC.
       Reading whole node and it's compressed - read into comprbuf, check
       CRC and decompress to buffer provided 
       Reading partial node and it's uncompressed - read into readbuf,
       check CRC, and copy 
       Reading partial node and it's compressed - read into readbuf, 
       check checksum, decompress to decomprbuf and copy
    */
    if (ri->compr == JFFS2_COMPR_NONE && (uint32_t)len == je32_to_cpu(ri->dsize)) {
        readbuf = buf;
    }
    else {
        readbuf = (unsigned char *)kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
        if (!readbuf) {
            ret = ENOMEM;
            goto out_ri;
        }
    }
    if (ri->compr != JFFS2_COMPR_NONE) {
        if ((uint32_t)len < je32_to_cpu(ri->dsize)) {
            decomprbuf = (unsigned char *)kmalloc(je32_to_cpu(ri->dsize),
                            GFP_KERNEL);
            if (!decomprbuf) {
                ret = ENOMEM;
                goto out_readbuf;
            }
        }
        else {
            decomprbuf = buf;
        }
    }
    else {
        decomprbuf = readbuf;
    }

    D2(printk(KERN_DEBUG "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
              readbuf));
    ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
                           je32_to_cpu(ri->csize), &readlen, readbuf);

    if (!ret && readlen != je32_to_cpu(ri->csize))
        ret = EIO;
    if (ret)
        goto out_decomprbuf;

    crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
    if (crc != je32_to_cpu(ri->data_crc)) {
        printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at"
                        " %08x\n", je32_to_cpu(ri->data_crc), crc,
                        ref_offset(fd->raw));
        ret = EIO;
        goto out_decomprbuf;
    }
    D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
    if (ri->compr != JFFS2_COMPR_NONE) {
        D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n",
                  je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize),
                                  decomprbuf));
        ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf,
                        decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
        if (ret) {
            printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
            goto out_decomprbuf;
        }
    }

    if ((uint32_t)len < je32_to_cpu(ri->dsize)) {
        memcpy(buf, decomprbuf+ofs, len);
    }
out_decomprbuf:
    if (decomprbuf != buf && decomprbuf != readbuf)
        kfree(decomprbuf);
out_readbuf:
    if (readbuf != buf)
        kfree(readbuf);
out_ri:
    jffs2_free_raw_inode(ri);

    return ret;
}

int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
                unsigned char *buf, uint32_t offset, uint32_t len)
{
    uint32_t end = offset + len;
    struct jffs2_node_frag *frag;
    int ret;

    D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",
              f->inocache->ino, offset, offset+len));

    frag = jffs2_lookup_node_frag(&f->fragtree, offset);

    /* XXX FIXME: Where a single physical node actually shows up in two
       frags, we read it twice. Don't do that. */
    /* Now we're pointing at the first frag which overlaps our page */
    while (offset < end) {
        D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n",
                        offset, end));
        if (unlikely(!frag || frag->ofs > offset)) {
            uint32_t holesize = end - offset;
            if (frag) {
                D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. "
                                "frag->ofs = 0x%08x, offset = 0x%08x\n",
                                f->inocache->ino, frag->ofs, offset));
                holesize = min(holesize, frag->ofs - offset);
            }
            D1(printk(KERN_DEBUG "Filling non-frag hole from %d-%d\n", offset,
                            offset + holesize));
            memset(buf, 0, holesize);
            buf += holesize;
            offset += holesize;
            continue;
        }
        else if (unlikely(!frag->node)) {
            uint32_t holeend = min(end, frag->ofs + frag->size);
            D1(printk(KERN_DEBUG "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n",
                            offset, holeend, frag->ofs, frag->ofs + frag->size));
            memset(buf, 0, holeend - offset);
            buf += holeend - offset;
            offset = holeend;
            frag = frag_next(frag);
            continue;
        }
        else {
            uint32_t readlen;
            uint32_t fragofs; /* offset within the frag to start reading */

            fragofs = offset - frag->ofs;
            readlen = min(frag->size - fragofs, end - offset);
            D1(printk(KERN_DEBUG "Reading %d-%d from node at 0x%08x (%d)\n",
                      frag->ofs+fragofs, frag->ofs+fragofs+readlen,
                      ref_offset(frag->node->raw), ref_flags(frag->node->raw)));
            ret = jffs2_read_dnode(c, f, frag->node, buf,
                            fragofs + frag->ofs - frag->node->ofs, readlen);
            D2(printk(KERN_DEBUG "node read done\n"));
            if (ret) {
                D1(printk(KERN_DEBUG"jffs2_read_inode_range error %d\n",ret));
                memset(buf, 0, readlen);
                return ret;
            }
            buf += readlen;
            offset += readlen;
            frag = frag_next(frag);
            D2(printk(KERN_DEBUG "node read was OK. Looping\n"));
        }
    }
    return 0;
}
